STEVE INSKEEP, host:
It's MORNING EDITION from NPR News. I'm Steve Inskeep. We've been looking into some of the downsides of green energy. The government has already spent a lot of effort on biofuels. Now, lawmakers are considering how to encourage billions of dollars of investment on alternatives, from ethanol to wind to solar energy. Even as they consider the possibilities, new analysis by environmental experts shows alternative energy comes with stiff costs. Here's NPR's Christopher Joyce.
CHRISTOPHER JOYCE: Rob McDonald says people used to laugh when he argued that remaking the energy economy could affect millions of acres of land. As a landscape ecologist at the Nature Conservancy, McDonald decided to prove his point. He analyzed the energy law passed in 2007 that called for billions of gallons of ethanol from corn to replace gasoline. He also looked at two climate bills that encourage alternative energy. What he found was a prescription for what he calls energy sprawl.
Mr. ROB MCDONALD (Landscape ecologist, Nature Conservancy): Whenever you switch to renewables, the amount of space it takes to make that energy will go up.
JOYCE: Renewables like wind turbines, dams, big solar collectors and, most of all, millions of acres of corn for ethanol or soybeans to make diesel fuel. That's because wind farms or corn fields take up more room than coal mines or nuclear power plants for the amount of energy you get out. McDonald calculated how much land is needed to get one terawatt hour of energy - about what you'd get in a year from a small power plant - from coal plants and dams and wind farms and other sources.
Mr. MCDONALD: To get a terawatt hour from coal, you need 9.7 square kilometers, on average. And then for wind power it, takes about 72 square kilometers. And by the time you get up to something like corn ethanol, it's like 350 square kilometers.
JOYCE: And more ethanol is in our future. The government's energy analysts say the country could be producing 10 billion gallons of renewable fuel from crops by 2030.
Mr. MCDONALD: You'd need about 23 million acres of corn to meet that, which is about the size of Indiana. So it's a big chunk of area.
JOYCE: The climate and energy bill now in the Senate encourages more ethanol and other crop fuels, as well as a lot more wind and solar energy. Martha Groom, a biologist at the University of Washington who's reviewed the research, says all of that could mean less land for other things.
Professor MARTHA GROOM (Biologist, University of Washington): I think that it should be a very big wakeup call that this is going to have large impacts on our native habitats and on biodiversity, and that we should be looking a lot harder at how we could reduce energy consumption.
JOYCE: Groom says when uncultivated land gets converted to make energy, whether it's for solar collectors or corn fields, you lose some of the services that land provided, filtering water or providing habitat for wildlife. Another drawback with energy sprawl is that energy crops may displace food crops. But ethanol advocate Bob Dinneen, who runs the Renewable Fuels Association, says all these arguments exaggerate ethanol's footprint.
Mr. BOB DINNEEN (Renewable Fuels Association): The land use from ethanol worldwide last year was less than six-tenths of one percent of available crop land. I mean, that is miniscule.
JOYCE: Dinneen says American farmers will probably only plant another five million acres of land to meet the mandate for renewable fuels. He says improvements in corn yields per acre and in the manufacture of ethanol in factories should minimize the need for more land.
Study author Rob McDonald, who published the research in the journal PLoS One, says he's not arguing against alternative forms of energy, only that some forms create less sprawl than others. He notes that the one that uses the least amount of land is efficiency, simply using less energy than we do now.